The invention relates to a protective cover for a cutting wheel of a hand-held cut-off machine driven by an internal combustion engine, wherein the protective cover comprises a circumferential wall and two opposed sidewalls adjoining the circumferential wall.
Small hand-held circular saws are known in which the circular saw wheel is enclosed relative to the operator by a protective cover made of cast light metal. The protective cover provides a contact protection and serves for catching or removing by suction the relatively lightweight sawdust. The protective cover as a whole is exposed only to minimal operating loads.
When performing a cut in stone or similar materials, hand-held cut-off machines generate large amounts of grinding dust that can also be mixed with coarse particles. For collecting the grinding dust, the particles, and optionally also sparks that are generated, a protective cover is provided that partially covers the cut-off wheel of the cut-off machine.
In particular in the case of large cut-off machines that are driven by an internal combustion engine and have cutting wheels having a diameter, for example, of 300 mm or 350 mm, a significant driving power is required for performing a cut. The great power output causes large amounts of dust, particles, sparks or the like that are swirled at extremely high kinetic energy and thrown against the inner side of the protective cover of the cutting wheel. Making things worse is the fact that the stone or cement dust or the like has a high abrasive effect that, in combination with the great kinetic energy, leads to a correspondingly high wearing load on the protective cover.
In addition to be thus resulting requirement of a high wear resistance, the weight of the cover is of particular importance. Cut-off machines having an internal combustion engine as the drive motor belong to a size class that, based on the configuration, have a higher inherent weight in comparison to smaller devices. In order to enable, in spite of this, excellent handling in the case of manually performed cutting tasks, a lightweight construction for compensation of the high concept-based basic weight is a primary objective.
DE 295 08 950 discloses that the protective cover of a cut-off machine of the aforementioned kind made of aluminum is correspondingly lightweight but does not fulfill the requirements in regard to a long service life and wear resistance. As a solution to this problem, the aforementioned document proposes a two-part protective cover that is joined of aluminum sheet and has a wear strip riveted into its circumferential wall. The rivet connection secures the wear strip and serves at the same time for providing a connection of the two cover parts made of aluminum sheet. A cover of such a configuration is comparatively lightweight and has also an improved wear resistance. The service life however is limited because of the rivet heads that project into the interior of the cover and are exposed to the grinding dust and thus to abrasion.
The invention has the object to provide a protective cover for a cutting wheel of a hand-held cut-off machine which provides improved wear resistance while being made of a lightweight construction.